Stress indices for ANSI standard B16.11 socket-welding fittings

73 Pages·2012·1.53 MB·English

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ORNL-TM-4929
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OAKRIDGENATIONALLABORATORYLIBRARY
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Stress Indices for ANSI Standard B16.11
Socket-Welding Fittings
E. C. Rodabaugh
S. E. Moore
Printed in the United StatesofAmerica. Availablefrom
National Technical Information Service
U.S. Department ofCommerce
5285 Port Royal Road, Springfield, Virginia22161
Price: Printed Copy $5.45; Microfiche$2.25
This report was prepared as an account of work sponsored by the United States
Government. Neither the United States nor the Energy Research and Development
Administration, nor any of their employees, nor any of their contractors,
subcontractors, or their employees, makes any warranty, express or implied, or
assumes any legal liability or responsibility for the accuracy, completeness or
usefulness of any information, apparatus, product orprocessdisclosed, orrepresents
that its usewould not infringe privatelyowned rights.
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~
ORNL-TM-lj-929
UC-79, -79H, -79k
Contract No. W-7U05-eng-26
Reactor Division
STRESS INDICES FOR ANSI STANDARD Bl6.ll
SOCKET-WELDING FITTINGS
E. C. Rodabaugh
Battelle-Columbus Laboratories
S. E. Moore
Oak Ridge National Laboratory
AUGUST 1975
Subcontract No. 29I3
for
OAK RIDGENATIONALLABORATORYLIBRARY
OAK RIDGE NATIONAL LABORATORY
Oak Ridge, Tennessee 3783O
operated by 3 44Stj Q023EA3 i|
UNION CARBIDE CORPORATION
for the
U.S. ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATION

Ill
CONTENTS
Page
FOREWORD v
ABSTRACT 1
1. INTRODUCTION 1
Purpose and Scope 1
Nomenclature 5
2. ANSI Bl6.ll STANDARD DIMENSIONAL REQUIREMENTS 7
3. DIMENSIONS OF SOME Bl6.11 FITTINGS 10
k. PRESSURE-TEMPERATURE RATINGS AND PIPE EQUIVALENCE 21
Standard Pressure Ratings 21
Pipe Equivalence 24
5. STRESS INDICES FOR INTERNAL PRESSURE 26
Primary-Stress Bx Indices 26
Primary-Plus-Secondary and Peak-Stress Indices 28
6. STRESS INDICES FOR MOMENT LOADINGS 33
Socket-Welding Tees 3^
Socket-Welding Elbows 35
Socket-Welding Couplings 36
Summary of Proposed Stress Indices for Moment
Loadings 36
Comparison of Design Fatigue Lives for Socket-Welding
Fittings and Girth Fillet Welds 38
7. STRESS INDICES FOR THERMAL LOADINGS 47
8. SUMMARY AND RECOMMENDATIONS 50
9. ACKNOWLEDGMENTS 55
10. REFERENCES 56
APPENDIX A. PROPOSED CODE CASE ON STRESS INDICES FOR
SOCKET-WELDING FITTINGS 57
APPENDIX B. SURVEY OF FAILURES ASSOCIATED WITH SOCKET AND
FILLET WELDS IN NUCLEAR-POWER-PLANT PIPING SYSTEMS 59

V
FOREWORD
The work reported here was performed at Oak Ridge National Laboratory
(ORNL) and at Battelle-Columbus Laboratories under Union Carbide Corpora
tion Nuclear Division subcontract No. 2913, as part of the ORNL Piping
Program — Design Criteria for Piping, Pumps, and Valves — under the direc
tion of W. L. Greenstreet, Technical Director, Solid Mechanics Department.
The program is funded by the U.S. Energy Research and Development Admin
istration (ERDA) as the government-supported portion of a cooperative ef
fort with industry for the development of design criteria for nuclear-
power-plant piping components. This joint effort is coordinated by the
Pressure Vessel Research Committee (PVRC) of the Welding Research Council,
under the Subcommittee on Piping, Pumps, and Valves. B. C. Wei, ERDA Di
vision of Reactor Research and Development, is the Cognizant Engineer.
Prior reports and open-literature publications under the ORNL piping
program are listed below.
1. W. L. Greenstreet, S. E. Moore, and E. C. Rodabaugh, "Investigations
of Piping Components, Valves, and Pumps to Provide Information for
Code Writing Bodies, " ASME Paper 68-WA/PTC-6, American Society of
Mechanical Engineers, New York, Dec. 2, I968.
2. W. L. Greenstreet, S. E. Moore, and R. C. Gwaltney, Progress Report
on Studies in Applied Solid Mechanics, ORNL-4576 (August 1970).
3. E. C. Rodabaugh, Phase Report No. II5-I on Stress Indices for Small
Branch Connections with External Loadings, ORNL-TM-3OI4 (August 1970).
4. E. C. Rodabaugh and A. G. Pickett, Survey Report on Structural Design
of Piping Systems and Components, TID-25553 (December 1970).
5. E. C. Rodabaugh, Phase Report No. II5-8, Stresses in Out-of-Round Pipe
Due to Internal Pressure, ORNL-TM-3244 (January 1971)•
6. S. E. Bolt and W. L. Greenstreet, "Experimental Determination of Plas
tic Collate Loads for Pipe Elbows," ASME Paper 7I-PVP-37, American
Society of Mechanical Engineers, New York, May 1971-
7. G. H. Powell, R. W. Clough, and A. N. Gantayat, "Stress Analysis of
BI6.9 Tees by the Finite Element Method," ASME Paper 71-PVP-40, Ameri
can Society of Mechanical Engineers, New York, May 1971-
8. J. K. Hayes and B. Roberts, "Experimental Stress Analysis of 24-Inch
Tees," ASME Paper 71-PVP-28, American Society of Mechanical Engineers,
New York, May I97I.
VI
*9. J. M. Corum et al., "Experimental and Finite Element Stress Analysis
of a Thin-Shell Cylinder-to-Cylinder Model," ASME Paper 7I-PVP-36,
American Society of Mechanical Engineers, New York, May 1971.
10. W. L. Greenstreet, S. E. Moore, and J. P. Callahan, Second Annual
Progress Report on Studies in Applied Solid Mechanics (Nuclear
Safety), ORNL-4693 (July 1971).
11. J. M. Corum and W. L. Greenstreet, "Experimental Elastic Stress Anal
ysis of Cylinder-to-Cylinder Shell Models and Comparisons with Theo
retical Predictions," Paper No. G2/5, First International Conference
on Structural Mechanics in Reactor Technology, Berlin, Germany,
Sept. 20-24, 1971.
12. R. W. Clough, G. H. Powell, and A. N. Gantayat, "Stress Analysis of
BI6.9 Tees by the Finite Element Method," Paper No. F4/7, First In
ternational Conference on Structural Mechanics in Reactor Technology,
Berlin, Germany, Sept. 20-24, 1971.
13. R. L. Johnson, Photoelastic Determination of Stresses in ASA BI6.9
Tees, Research Report 7I-9E7-PHOTO-R2, Westinghouse Research Labo
ratory (November 1971)•
14. E. C. Rodabaugh and S. E. Moore, Phase Report No. 115-10 on Compari
sons of Test Data with Code Methods for Fatigue Evaluations, 0RNL-
TM-352O (November 1971).
15. W. G. Dodge and S. E. Moore, Stress Indices and Flexibility Factors
for Moment Loadings on Elbows and Curved Pipe, ORNL-TM-3658 (March
1972).
16. J. E. Brock, Elastic Buckling of Heated, Straight-Line Piping Con
figurations, ORNL-TM-3607 (March 1972).
17. J. M. Corum et al., Theoretical and Experimental Stress Analysis of
ORNL Thin-Shell Cylinder-to-Cylinder Model No. 1, 0RNL-4553 (October
1972).
18. W. G. Dodge and J. E. Smith, A Diagnostic Procedure for the Evaluation
of Strain Data from a Linear Elastic Test, ORNL-TM-34I5 (November
1972).
19. W. G. Dodge and S. E. Moore, "Stress Indices and Flexibility Factors
for Moment Loadings on Elbows and Curved Pipe," Welding Research
Council Bulletin 179, December 1972.
20. W. L. Greenstreet, S. E. Moore, and J. P. Callahan, Third Annual Prog
ress Report on Studies in Applied Solid Mechanics (Nuclear Safety),
ORNL-4821 (December 1972).
VI1
21. W. G. Dodge and S. E. Moore, ELB0W: A Fortran Program for the Cal
culation of Stresses, Stress Indices, and Flexibility Factors for
Elbows and Curved Pipe, ORNL-TM-4098 (April 1973).
22. W. G. Dodge, Secondary Stress Indices for Integral Structural Attach
ments to Straight Pipe, ORNL-TM-3476 (June 1973)- Also in Welding
Research Council Bulletin I98, September 1974.
23. E. C. Rodabaugh, W. G. Dodge, and S. E. Moore, Stress Indices at Lug
Supports on Piping Systems, ORNL-TM-4211 (May 1974). Also in Welding
Research Council Bulletin I98, September 1974.
24. W. L. Greenstreet, S. E. Moore, and J. P. Callahan, Fourth Annual
Progress Report on Studies in Applied Solid Mechanics (Pressure Ves
sels and Piping System Components), ORNL-4925 (July 1974).
25. R. C. Gwaltney, CURT-II — A Computer Program for Analyzing Curved
Tubes or Elbows and Attached Pipes with Symmetric and Unsymmetric
Loadings, ORNL-TM-4646 (October 1974).
26. E. C. Rodabaugh and S. E. Moore, Stress Indices and Flexibility Fac
tors for Concentric Reducers, ORNL-TM-3795 (February 1975).
27. R. C. Gwaltney, S. E. Bolt, and J. W. Bryson, Theoretical and Experi
mental Stress Analysis of ORNL Thin-Shell Cylinder-to-Cylinder Model h,
ORNL-5OI9 (June 1975).
28. R. C. Gwaltney, J. M. Corum, S. E. Bolt, and J. W. Bryson, Theoretical
and Experimental Stress Analyses of ORNL Thin-Shell Cylinder-to-
Cylinder Model 3, ORNL-5020 (June 1975).
STRESS INDICES FOR ANSI STANDARD Bl6.ll
SOCKET-WELDING FITTINGS
E. C. Rodabaugh S. E. Moore
ABSTRACT
Stress indices for ANSI standard Bl6.ll socket-welding tees,
1^-5° elbows, 90° elbows, and couplings are developed for intended
use with the Class-1 piping system design rules of Section III -
Division 1 of the ASME Boiler and Pressure Vessel Code. Indices
are given for the evaluation of appropriate primary stresses,
primary-plus-secondary stresses, and peak stresses due to inter
nal pressure, bending-moment loads, and thermal gradients between
the fitting and the attached pipe. The proposed indices are
based on the dimensional and pressure-burst requirements of the
Bl6.ll standard, the apparent shapes of Bl6.ll fittings as indi
cated from a random sampling taken off-the-shelf, the standard
pressure-temperature ratings of the fittings, and on current
stress indices now in the Code for similar butt-welding fittings.
Specific recommendations are made for issuing the new stress in
dices in a Code case.
Key words: stress indices, stress analysis, straight pipe,
elbows, socket-welding fittings, socket-welded joints, tees,
couplings, fillet welds, piping code, ASME BPVC Section III,
ANSI-Bl6.ll, nuclear piping, pressure-vessel code, ORNL piping
program.
1. INTRODUCTION
Purpose and Scope
Both socket-welding and threaded fittings are permitted for use in
Class-1 nuclear piping systems by Section III, Division 1 of the ASME
Boiler and Pressure Vessel Code,1 provided they are manufactured in accor
dance with the ANSI standard Bl6.ll, "Forged Steel Fittings, Socket-Weld
ing and Threaded."2'3 Specifically, paragraph NB-36U9* of the Code accepts
*In this report, reference to articles, subarticles, paragraphs, ta
bles, or figures from Section III, Division 1 of the ASME Boiler and Pres
sure Vessel Code are identified by number (e.g., NB-xxxx), as appropriate.
Hereafter Section III, Division 1 will be referred to simply as "the Code."